Reduced integrin α3 expression as a factor of poor prognosis of patients with adenocarcinoma of the lung

Purpose: We investigated the possible association between integrin alpha 3 and motility-related protein (MRP-1), cluster of differentiation antigen 9 (CD9) gene expression in non-small-cell lung cancer (NSCLC) and evaluated the prognostic significance of integrin alpha 3 expression. Patients and Methods: We performed a retrospective study of integrin alpha 3 and MRP-1/CD9 expression in resected tumor tissues from 151 NSCLC patients using quantitative reverse-transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry. Results: The ratio of integrin alpha 3/beta-actin expression ranged from 0 to 5.87 (mean was 0.80; median, 0.70). Using the cutoff value of 0.7, there were 78 (52%) integrin alpha 3-positive tumors and 73 (48%) tumors with reduced integrin alpha 3 expression. The immunohistochemical results agreed well with those of the RT-PCR assays, and 88% had no discrepancy, In case of discrepancy, the results of RT PCR were used in specimen classification. Integrin alpha 3 gene expression was independent from MRP-1/CD9 gene expression. No significant association was found between integrin alpha 3 expression and the patients' clinical characteristics. The overall survival rate of patients with integrin alpha 3-positive NSCLCs was only slightly better than that of individuals whose tumors had reduced integrin alpha 3 expression (55.9% v 47.1%; P =.085). By comparison, the overall survival rate of patients with integrin alpha 3-positive adenocarcinomas was strikingly greater than in those whose tumors had reduced gene expression (54.4% v 35.2%; P=.004). Multivariate analysis with the Cox regression model of NSCLC and adenocarcinoma indicated that integrin alpha 3 expression correlated better (P =.0188 and P=.0008, respectively) with the overall survival rate than other variables, except lymph node status. Conclusion: No significant association was found between integrin alpha 3 and MRP-1/CD9 gene expression in lung cancer. However, reduced integrin alpha 3 expression is a poor prognosis factor in patients with adenocarcinomas. (C) 1998 by American Society of Clinical Oncology.